|By Steve Gorman

(Reuters) - Missouri Governor Eric Greitens, already facing an invasion-of-privacy trial next month in connection with an extramarital affair, was charged separately on Friday with felony computer tampering tied to his political fund-raising.

The new case was brought by the same St. Louis prosecutor two days before the statute of limitations deadline for the charge, which stems from Greitens' alleged theft of a donor list from the military veterans charity he created and ran for several years.

Greitens, a Republican under mounting pressure from Missouri politicians of both parties to resign since the sex scandal broke earlier this year, called the latest case part of a "smear" campaign orchestrated by St. Louis Circuit Attorney Kim Gardner, a Democrat.

The governor, a former U.S. Navy SEAL commando once seen as a rising star in the GOP, vowed to clear his name in court, declaring, "People will know the truth."

His attorney Ed Dowd called the latest allegation against Greitens "absurd" and said his client was innocent.

"Now he's being accused of stealing an email list from an organization he built? Give me a break," Dowd said in a statement. "Not only did he create this list donor, by donor, friend by friend, but (the charity) still has the list."

The prosecutor's office issued a summons for the governor to appear in court, rather than an arrest warrant, allowing Greitens to turn himself in for booking, a spokeswoman for Gardner said. She said the city attorney's office would coordinate with Greitens' defense team for his surrender.

A similar process was followed when Gardner brought an invasion of privacy indictment against Greitens in February - a case slated to go to trial on May 10.

According to Friday's criminal complaint, the electronic theft occurred in April 2015, about a month after the privacy offense was alleged to have occurred, while Greitens was running for governor.

The complaint and accompanying "probable cause" statement accuse Greitens of felony computer data tampering to obtain and transmit the donor list of the veterans charity The Mission Continues without permission for his own political gain.

According to court documents in the case, Greitens directed another individual to obtain the donor list and furnish it to a fundraiser who was working on behalf of Greitens' gubernatorial campaign.

The charity's employee handbook and its non-disclosure agreements "prohibited disclosure of the donor list and the retention of it by anyone not employed by and working on behalf of The Mission Continues," the probable cause statement said.

Prosecutors did not say whether anyone else faced charges in the investigation.

A growing number of Missouri's elected officials, Democrats and Republicans alike, have called for Greitens' ouster since he was charged in an unrelated case in which he was accused of taking a compromising photo of a woman with whom he was involved without her consent and threatening to blackmail her with it.

Both the invasion of privacy and computer tampering charges are felonies, each punishable by up to four years in prison.

Greitens, 44, a married father of two has acknowledged a months-long affair but denied any criminal wrongdoing, asserting he is the victim of a political witch hunt. He has said he intends to remain in office while he fights to prove his innocence.

A St. Louis judge on Thursday denied a motion by Greitens' attorneys to dismiss the privacy charge against him.